1. Field of the Invention
The present invention relates to a sealing device according to a sealing technology. The sealing device according to the present invention is used, for example, in hydraulic and pneumatic equipment which accompanies a rotary motion, an oscillating motion or a reciprocating motion, or is used in various equipment which requires the sealing device for the purpose of the rotary motion, the oscillating motion or the reciprocating motion.
2. Description of the Conventional Art
A sealing device shown in FIG. 2 has been conventionally known as the sealing device for the rotary motion, the oscillating motion or the reciprocating motion. Since the sealing device generates a seal surface pressure by pressing a resin seal ring 51 which is made of PTFE to the other seal surfaces 52 and 53, the sealing device uses a spring means 54 constructed by a rubber ring such as an O-ring together (refer to Japanese Unexamined Patent Publication No. 11-78851).
However, in the case that a rigidity in a circumferential direction of the seal ring 51 is inferior, or in the case that a pressing force by the spring means 54 comes short, the seal ring 51 deforms in an inner peripheral direction according to some magnitude of a pressure (a sealing fluid pressure) acting on an outer peripheral portion of the seal ring 51, and a clearance is generated in an outer peripheral side of the seal ring 51. The clearance forms a leak route and the pressure may sometimes leak.
In order to inhibit the seal ring from deforming in the inner peripheral direction, it is thought to arrange a support ring 21 constructed by a rigid member such as a metal in an inner peripheral side of a seal ring 11 as shown as a comparative example in FIG. 3, thereby supporting the seal ring 11 from an inner peripheral side thereof by the support ring 21.
More specifically, the sealing device according to the comparative example in FIG. 3 is structured such as to be installed to an annular installation groove 3 which is provided in an outer peripheral surface 1a of one member 1 among two members 1 and 2 which are relatively moved, and come into close contact with the other member 2 which is positioned in an outer peripheral side of the installation groove 3 and one side wall of the installation groove 3, thereby sealing between two members 1 and 2. The sealing device has the resin seal ring 11 made of the PTFE, the support ring 21 constructed by the rigid member such as the metal, and a rubber ring 31 which serves as a spring means, as its constructing elements.
The seal ring 11 is provided with an outer peripheral surface 11a which slidably comes into close contact with the other member 2 and is formed into a cylindrical surface, an end surface 11b which is provided in one side in an axial direction and comes into close contact with the one side wall 3a of the installation groove 3 and is formed into an axially vertical plane shape, an inner peripheral surface 11c which is formed into a cylindrical surface shape, and an end surface 11d which is provided in the other side in the axial direction and is formed into an axially vertical plane shape, and is formed into a rectangular shape in its half cut surface. Further, a pressed surface 12 formed into a taper surface is provided in an inner peripheral corner portion which is provided in the other side in the axial direction. The inner peripheral surface 11c and the end surface 11d in the axially other side intersect at the inner peripheral corner portion.
On the other hand, the support ring 21 is provided in its outer peripheral surface with a pressing surface 22 formed into a taper surface shape in correspondence to the pressed surface 12 formed into the taper surface shape, and is structured such as to press the seal ring 11 to the other member 2 and the one side wall 3a of the installation groove 3 by being pressed by the rubber ring 31.
Therefore, on the basis of the sealing device according to the comparative example mentioned above, since the support ring 21 constructed by the rigid member such as the metal achieves a function of supporting the resin seal ring 11 from its inner peripheral side, the seal ring 11 is inhibited from deforming in the inner peripheral direction even if the pressure P is applied.
However, in the sealing device according to the comparative example mentioned above, there is further room for improvement in the following points.
More specifically, the sealing device according to the comparative example is structured, as mentioned above, such that the pressing surface 22 which is provided in the support ring 21 and is formed into the taper surface shape presses the pressed surface 12 which is provided in the seal ring 11 and is formed into the taper surface shape in the same manner, thereby pressing the seal ring 11 to the other member 2 and the one side wall 3a of the installation groove 3. Therefore, it is necessary to precisely process the pressing surface 22 and the pressed surface 12 which are both formed into the taper surface shape. If the precision of processing is not good and a contact state between both the surfaces 12 and 22 is not good, a clearance is generated between both the surfaces 12 and 22, a pressure resistance is lowered due to the clearance, and it becomes hard to secure a sealing performance.